Dipper-arm for steam shovels, dredges, and the like.



A. W. ROBINSON.

DIPPEB ARM FOB STEAM SHOVBLS, DRBDGES, AND THE LIKE.

APPLICATION FILED PEB.19, 1912.

Patented Dec.24, 1912.

UNITED STATES PATENT OFFICE.

ARTHUR W. ROBINSON, OF MONTREAL, QUEBEC, CANADA.

Duran-Arm FOR STEAM sn'ovnns, mmmms, AND THE LIKE.

Specification of Letters Iatent. Patented Dec, 24, 1912,

Application filed February 19, 1912. Serial No. 878,689.

to which it is liable in use may not result in injury either to it or to other parts of the mechanism. a

In the drawings, Figure 1 illustrates an elevation of that part of the machine, which co-acts with the dipper arm; Fig. 2 illustrates a plan view of that which is shown in 'Fig. 1; FigsJ3, 4 5 and 6 illustrate respectively cross sectional views of dipper arms embodying modified constructions of the invent-ion.

Figs. 1 and 2 are introduced merely to show generally the parts which co-act with the dipper arm and the relation it bears to the other parts of the mechanism, that a more clear understanding of the invention 80 may be had. -The dipper arm may be made --in a variety of ways all embodying the fundamental features of the invent-ion. Four of them are illustratedrespectively in Figs. 3, 4, 5 and 6.

Referring first to Figs. 1 and 2, 1 represents the boom. In the illustration shown this is a duplex or two part structure shown better in Fig. 2. Atits lower end it is suitably supported upon the usual turntable, or

40 equivalent device, not shown. 2 is the dipper, 3 the dipper arm, 4 one part of a duplex, or two part hoisting rope, shown better in Fig. 2, the two parts of which pass over uide sheaves 5, 5, and 6, 6; 7 is a =spreading and equalizing, sheave for the duplex hoisting rope which may be connected to the dipper by a pivoted frame 8 and bracket-9, as shown. 10 is a stay rod. 11 is a strap for theconfinement of the dipper arm, 12 is a roller with which the dipper arm engages for its more smooth operation.

Referring now to Figs. 3, 4, 5 and 6, dipper arms must necessarily have a certain amount of flexibility, because in operation they are inevitably subjected to many twistmg and 'bending strains and as heretofore constructed, they usually lack the requisite degree of flexibility, with the frequent result that the arm has either broken or else .has attained a set, as it is called, and refused to return to initial shape and condition; in

other words, the material of whichthe arm is composed has been so affected by the excessive twisting or bending as to attain and retain permanently a distorted form and it is the purpose of this invention to construct dipper arms on a new principle; that is tosay, built up of a succession of plates or laminae which may be all metal or all wood, but preferably. combined metal and wood, so arranged that when the deforming strains are applied to the arm, in recovering therefrom these laminae will slightly slip or slide over each other, thus individually adjusting themselves to the strain somewhat after the manner of the several leaves of the semi-elliptic spring. Thus, when the weight and strain are relieved, these several laminae will individually. exert their resiliency and secure an effective return of the arm to its original shape and condition, and in order that this action of the laminae may more effectively result, I prefer that they should be arranged vertically and the bolts connecting them horizontally, that is to say, extend from side to side. This construction is not arbitrary, because the ad vantages of the invention may be realized, measurably at least, if the laminae and the bolts run in the reverse directions.

The degree of movement or sliding of the laminae over each other will be necessarily' slight and the engagement or the,

bolts with the several laminae, particularly if some of them are made of wood, is such that there will be sufiicient give and take to avoid any injurious shearing action.

Referring now to Figs. 3 to 6, inclusive, it

will be understood that the roller 12 shown in Fig. 1 or its equivalent, engages with the under surface of the arms illustrated in these figures. In Fig. 3 the arm is built up of laminae as follows: 13, 13, are the two side'plates, preferably of steel, or other suitable metal. 14, 14, are eye beams. In this instance there are three. Between these metal parts, wooden or timber laminae 15, 15, are fitted, and the whole is bound together by cross bolts 16, 16, which pass from side to side through all the laminae and are suitable headed or riveted, as shown. It

' be noted that when twisting or lateral the top and bottom of the eye beams-14 are so narrow that they also will flex to the able guiding sheaves, as shown in those fig-.

degree necessary without rupture or attainin a set. I he construction shown in Fig. 4 is substantially the same as that illustrated in Fig. 3, except that the metal laminae are in this instanceshown as all in the form of flat plates and the wooden laminae are correspondingly shaped to effect a continuous square outline or shape of the structure.

In Fig. 5 I illustrate a combination of that which is shown in Figs. 3 and 4;, that is to 1 say, the outside plates 13, 13, are reinforced at thecorners with small angle Iron strips 17, 17, which are riveted, bolted or welded to the plates 13. These angle irons at the corners will not interfere with the desired flexibility of the arm because the flanges of the angle irons are so narrow as not to interfere with the bending or twisting of the arm and, indeed, will add to its elasticity, thus aiding in its return to initial conditions. These angle irons also increase the area of metal surface at the corners of the arm, thus strengthening it and adding to its durability. r

In Fig. 6 I show a construction which is similar to that shown in Fig. 5, excepting that the side plates 13 have narrow flan es 18 made integral with them instead of eilng separate pieces attached to them,-as in I prefer to use in the machines equipped with my improved dipper arm a duplex or two part hoist, as shown in Figs. land 2, so. that the boom being equipped with suitures, the two parts of the hoist may be spread apart, so that the dipper arm will worlr between them. Obviously, however, if

a single hoistin rope or chain be referred,

or it may then any suitab e guidingldevlilcesw y t e ipper am arated from each other by a space suflicient to permit the single hoist to work between them. In this event, as will be readil understood, each of the halves of the dlpper arm will embody the laminated constructions illustrated and described above.

It will be obvious to those who are familiar with such matters that modifications other than those disclosed herein may be made in the details of construction, without departing from the essentials of the inven: tion. I therefore do not limit myself to the specific constructions shown. The are presented as examples only of man orms in which the invention may be embo ied.

I claim: i

. 1. A dipper arm composed of a series of alternating wood and metal laminae bound together by bolts running horizontally and all in the same direction, the metal laminae being upon the outer side surface.

2. A dipper arm composed of a series of alternating laminae of wood and metal suitably bound together, some of the metal laminaehaving narrow flanges at their edges.

3. A dipper arm composed of a series of alternating wood and metal, laminae bound together by horizontally extending bolts, all running in the same direction, the outer side laminae being metal and provided with narrow flanges which inclose the corners of the arm.

In testimony whereof I have signed my name to this specification in two subscribing witnesses.

ARTHUR ROBINSON. Witnesses:

E. M. CoRBE'r, D. S. Cnmsrm.

e as abifurcated or two part the presence of 

